The present invention relates to wall and ceiling construction techniques, and more specifically to the use of resilient runner channels for dampening sound and retarding the progress of fire in such construction.
Conventional residential and office construction involves the erection of framing, typically wood or metal studs positioned vertically, and connected in spaced, parallel orientation to similarly formed headers and footers. Framing also includes floor or ceiling joists, to which are connected the headers and footers described above, often with subfloor panels in between. Next, wallboard panels, usually made of gypsum compositions faced with paper or the like on front and rear surfaces, are secured to the framing to form walls, and in many cases, ceilings as well. Wallboard joint compound and joint tape are used to fill and smooth the joints between adjacent wallboard panels as is well known in the art. Such construction techniques are suitable for single family residences, however, in the case of multi-family dwellings such as apartment buildings, dormitories, small hotels, barracks and the like, traditional room construction as described above is prone to the ready transmission of sound between rooms.
To address the problem of unwanted sound transmission between laterally adjacent rooms, and also between rooms stacked vertically, resilient channel was developed, as described in commonly-assigned U.S. Pat. No. 3,090,164, incorporated by reference. Such resilient channel, which over time has become known in the industry as RC-1 channel, has a pair of generally parallel, laterally displaced planar surfaces. Several lengths of the RC-1 channel are mounted to the framing, preferably studs or joists in spaced, parallel, horizontal orientation. A first such surface is referred to as a base, and is fastened to the framing members by nails, threaded fasteners or the like. An angled flange connects the first and second surfaces, and laterally displaces the second surface from the base. Wallboard panels are secured to the second surface, which is unattached to the framing member at the opposite end from the base. Thus, the wallboard panels are held suspended away from the framing members by the RC-1 channel.
By separating the wallboard panels from the framing, sound energy impacting the panels, which would normally be transmitted through the panels directly to the framing and distributed throughout the building, is dampened as it impacts the wallboard panels and has its transmission path interrupted by the RC-1 channel. Another advantage of RC-1 channel is that the progress of fire in a room built with the channels is impeded once the fire impacts the wallboard panels, since the flames and heat are not directly transmitted through the framing to other parts of the building.
Building codes, as well as Underwriter's Laboratories (UL) standards for the use of RC-1 channel, call for the use of 1-inch long fasteners, typically conventional wallboard screws or the like. However, in practice, applicators have become frustrated in using such fasteners to pass through the wallboard panels, and to intersect the flexible second surface of the RC-1 channel, which by design is movable. In some cases, the fastener tip encounters difficulty in locating a positive contact point, despite the fact that the fastener tip is self-tapping. Another factor reducing the use of 1-inch fasteners, is that this is an uncommon size for use on conventional building sites. Instead, the more popular size is 1¼-inch fasteners. It has also been found that when applicators use the longer fasters in installing wallboard panels to RC-1 channels, the fasteners extend through the second surface of the RC-1 channel and contact the underlying framing member, such as a stud or joist, thus forming an acoustic transmission pathway through the wall or ceiling, and significantly reducing the acoustic benefit of the RC-1 channel. Similarly, the longer fasteners also create conductive pathways from the wallboard panel to the framing member or frame member, so that in the case of fire, the progression of heat and flames through the framing is accelerated.
One attempted solution to the problem of installers using overly long fasteners has been to employ an acoustic isolator clip of the type disclosed in commonly-assigned US 2009/0173029, which is incorporated by reference. In that reference, the isolator clip has a thickness that spaces the RC-1 channel from the framing member, so that the longer fasteners do not reach the frame member. However, there has been some commercial resistance to the use of such isolator clips.
Accordingly, there is a need for an improved RC-1 channel which can accommodate longer fasteners while maintaining the desired acoustic dampening properties.